Multimode receiving devices are known, such as mobile or non-mobile devices that have transceivers that can communicate with differing types of wireless systems. For example, multimode receiving devices may include, for example, a cell phone, internet appliance, PDA, laptop, or any other suitable device that can communicate with differing wireless systems such as a TDMA cellular system and WCDMA cellular system. In addition, differing wireless systems may include a cellular system and a digital broadcast system. With differing systems that are not synchronized in the time domain, it can be difficult to ensure the coordination of information flow between the multiple systems and one or more multimode receiving devices, such as a mobile or non-mobile receiving device, to avoid loss of information since the processing load for the multimode receiving device increases when information is being sent simultaneously over both systems to a receiving device. Hence, more complicated and costly processors can be required in multimode receiving devices.
Some multimode receiving devices are known that have, for example, two independent receive chains (and transmit chains) such that they have dual receivers, one receiver dedicated to each of the different wireless systems. For example, with WCDMA and group special mobile systems (GSM) multimode systems, a multimode receiving device may scan and find, for example, the GSM system when the WCDMA system is operating in a discontinuous mode. For example, in a discontinuous mode, the WCDMA system is not in time synchronization with a GSM system and sooner or later, the multimode receiving device will locate a GSM channel, but the eventual location can waste bandwidth of a WCDMA transmission. As such, inefficient processing can occur.
Single mode systems are known such as a system that uses, for example, a global positioning satellite system to provide a synchronized time base for a cellular base site. However, such systems are single mode systems in that the receiving devices, such as the mobile devices, communicate via the cellular system only. Such GPS and cellular systems merely synchronize a single communication system, namely the cellular system, to a common GPS clock.
Also, it is known for cellular systems and other wireless systems to have a type of control channel that, for example, contains synchronization information to allow devices to synchronize to a cellular system. This may take, for example, the form of a paging channel or a timing synchronization channel or any other suitable channel or information. However, typically, such cellular synchronization data is not in synchronization with a different wireless system for a multimode receiving device. Accordingly, if a multimode receiving device, for example, is listening on its synchronization channel and the second wireless system, such as a digital broadcast system is broadcasting information, the broadcast information may not be detected by the multimode device or if detected, requires the device's processor to process information from both systems at essentially the same time.
For example, multimode systems are also known that have a mobile multimode receiving device that includes a receiver (and antenna) for receiving cellular information and another receive chain and an antenna combination for receiving digital broadcast information. However, if the multimode receiving device (which also may be a transmitting device if desired), receives digital broadcast information at the same time as it is listening to a cellular paging channel, the loading on the processor can be quite large.
It would be desirable to have an apparatus and method so that a less expensive processor may be used that would also potentially draw less current and for mobile devices, result in a longer lasting battery and a smaller device. Therefore, it would be desirable to better balance the processing load over time.